fix(lang): a function named like an engine namespace method's target is refused

Random.range is rng_range, so a package's own rng_range(a, b, c) took
every Random.range call silently. Where the program calls such a method
and the target resolves to a function of its own, the function is
refused, naming the namespace method and the call. Reseed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/rejected/engine_alias_name.ludic

@@ -0,0 +1,10 @@
+# a function named like the target of one of the engine's namespace methods would take that
+# method's calls: Random.range is rng_range, so this rng_range is refused where Random.range is used
+program EngineAliasName {
+  function rng_range(a: int, b: int, c: int) -> int {
+    return a + b + c
+  }
+  entry {
+    print(Random.range(1, 6))
+  }
+}